GH-1192 - Migrate code base to jSpecify for nullness verification.

spring-modulith-events/spring-modulith-events-api/pom.xml

@@ -17,6 +17,11 @@
 
 	<dependencies>
 
+		<dependency>
+			<groupId>org.jspecify</groupId>
+			<artifactId>jspecify</artifactId>
+		</dependency>
+
 		<dependency>
 			<groupId>org.springframework</groupId>
 			<artifactId>spring-context</artifactId>

spring-modulith-events/spring-modulith-events-api/src/main/java/org/springframework/modulith/events/AnnotationTargetLookup.java

@@ -25,6 +25,7 @@ import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.modulith.events.RoutingTarget.ParsedRoutingTarget;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -45,7 +46,7 @@ class AnnotationTargetLookup implements Supplier<Optional<ParsedRoutingTarget>>
 
 	private static Map<Class<?>, AnnotationTargetLookup> LOOKUPS = new ConcurrentReferenceHashMap<>(25);
 	private static final String JMOLECULES_EXTERNALIZED = "org.jmolecules.event.annotation.Externalized";
-	private static final Class<? extends Annotation> JMOLECULES_ANNOTATION = loadJMoleculesExternalizedIfPresent();
+	private static final @Nullable Class<? extends Annotation> JMOLECULES_ANNOTATION = loadJMoleculesExternalizedIfPresent();
 
 	private final Class<?> type;
 	private final Supplier<Optional<ParsedRoutingTarget>> lookup;
@@ -159,7 +160,7 @@ class AnnotationTargetLookup implements Supplier<Optional<ParsedRoutingTarget>>
 	}
 
 	@SuppressWarnings("unchecked")
-	private static Class<? extends Annotation> loadJMoleculesExternalizedIfPresent() {
+	private static @Nullable Class<? extends Annotation> loadJMoleculesExternalizedIfPresent() {
 
 		var classLoader = DefaultEventExternalizationConfiguration.class.getClassLoader();
 

spring-modulith-events/spring-modulith-events-api/src/main/java/org/springframework/modulith/events/EventExternalizationConfiguration.java

@@ -28,8 +28,8 @@ import java.util.function.BiPredicate;
 import java.util.function.Function;
 import java.util.function.Predicate;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.core.annotation.AnnotatedElementUtils;
-import org.springframework.lang.Nullable;
 import org.springframework.modulith.events.RoutingTarget.ParsedRoutingTarget;
 import org.springframework.modulith.events.RoutingTarget.RoutingTargetBuilder;
 import org.springframework.util.Assert;
@@ -359,7 +359,16 @@ public interface EventExternalizationConfiguration {
 		}
 
 		private static <T extends Annotation> T findAnnotation(Object event, Class<T> annotationType) {
-			return findMergedAnnotation(event.getClass(), annotationType);
+
+			var type = event.getClass();
+			var result = findMergedAnnotation(type, annotationType);
+
+			if (result == null) {
+				throw new IllegalStateException(
+						"Couldn't find annotation %s on type %s!".formatted(annotationType, type));
+			}
+
+			return result;
 		}
 	}
 

spring-modulith-events/spring-modulith-events-api/src/main/java/org/springframework/modulith/events/EventExternalized.java

@@ -17,9 +17,10 @@ package org.springframework.modulith.events;
 
 import java.util.Objects;
 
+import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.ResolvableTypeProvider;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -103,7 +104,7 @@ public class EventExternalized<S, T> implements ResolvableTypeProvider {
 	 *
 	 * @return can be {@literal null}.
 	 */
-	public T getBrokerResult() {
+	public @Nullable T getBrokerResult() {
 		return brokerResult;
 	}
 
@@ -112,7 +113,7 @@ public class EventExternalized<S, T> implements ResolvableTypeProvider {
 	 * @see org.springframework.core.ResolvableTypeProvider#getResolvableType()
 	 */
 	@Override
-	public ResolvableType getResolvableType() {
+	public @NonNull ResolvableType getResolvableType() {
 		return type;
 	}
 

spring-modulith-events/spring-modulith-events-api/src/main/java/org/springframework/modulith/events/RoutingTarget.java

@@ -17,7 +17,7 @@ package org.springframework.modulith.events;
 
 import java.util.Objects;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -238,14 +238,14 @@ public class RoutingTarget {
 		/**
 		 * @return the target
 		 */
-		public String getTarget() {
+		public @Nullable String getTarget() {
 			return target;
 		}
 
 		/**
 		 * @return the key
 		 */
-		public String getKey() {
+		public @Nullable String getKey() {
 			return key;
 		}
 

spring-modulith-events/spring-modulith-events-api/src/main/java/org/springframework/modulith/events/package-info.java

@@ -1,5 +1,5 @@
 /**
  * API of the event publication registry abstraction.
  */
-@org.springframework.lang.NonNullApi
+@org.jspecify.annotations.NullMarked
 package org.springframework.modulith.events;